EN
Cathodic Protection Installation Inspection
Periodic inspection of cathodic protection: reference electrode potential survey, anode-rectifier tests and coating holiday checks.
Cathodic protection installation periodic inspection audits the system that protects buried or immersed steel structures (pipelines, tank bottoms, jetty piles, quay steel) from corrosion by impressed current or sacrificial anodes: the protection potential is measured, anode and connection integrity are checked and conformity with the criteria standards is verified. A badly installed or untracked cathodic protection grows unseen pitting corrosion on the hidden surface, leading to leaks and loss of transfer capacity.
Control and Measurement Items
- Potential survey: Measuring structure-to-electrolyte potential at test points with a copper/copper-sulfate (Cu/CuSO₄) reference electrode; the -850 mV criterion (with IR drop) and instant-off evaluation.
- Impressed current source: Output voltage-current setting of the rectifier, timing and protection circuits; anode bed resistance.
- Sacrificial anode system: Continuity of anode-to-steel connections, measurement of consumption ratio and replacement decision.
- Coating/leakage: Coating continuity (holiday / DCVG / ACVG), integrity of isolation flanges, search for unintended contact with foreign structures (cross-coupling).
- Record: Trending CP monitoring data, survey map and comparison against the last report.
Legislation and Standards
Cathodic protection control is performed periodically within the maintenance duty of pressure installation operation (oil-gas, water, chemicals, ports) under Law No. 6331. Technical references: TS EN 12954 for buried metallic structures, TS EN 13636 for immersed structures, and NACE SP0169 with the relevant ISO/EN series for leakage and protection survey practice. Measurement criteria and acceptance limits are quantified in the standards the legislation cites. As an outcome, the system must document "adequate protection" before corrosion damage becomes visible.
Risks and Operator Recommendations
Frequent non-compliances: a rectifier that is "on but insufficient" (its current set point no longer meets the growing demand), potentials misread due to high contact resistance of the reference electrode, and current escaping to adjacent metal through a leaking isolation flange. Leaving test points rusty or dirty creates both false readings and real corrosion; test point cleaning must be tied to the periodic procedure. Pipeline routing must be marked ahead of new excavation works and CP test boxes kept undamaged in coordination with the operator. Annual review of trend data makes anode and power source replacement decisions economic.
Outcome
At the end of measurement, a signed report with the potential map, system performance card and recommendations is issued. Cathodic protection controls are within our Periodic Inspection of Installations group. For tank-farm installations review our Air Tank and Industrial Process Installations services, or contact us for a site survey.
FAQ on Cathodic Protection Inspection
Cathodic protection stops corrosion of steel surfaces in soil-water (pipe lines, tank bottoms, jetty-pile structures) by making the structure electrochemically a cathode (impressed current feed or sacrificial anodes). Protection current-potential vary with coating, soil resistivity and the year-drought-humidity regime: unmeasured or sinking levels let corrosion continue silently, which is why periodic monitoring of the installation is mandatory.
Structure-to-soil potential with a reference electrode (Cu/CuSO4, silver-chloride), CIP-test off-active, rectifier current-voltage-readout (impressed current-voltage-percentage), sacrificial anode potential-current-depletion control, test strip-junction box continuity, soil resistivity (Wenner) and stray current leakage control. Criteria follow the relevant standard-design specification; the classic measure is potential below -850 mV Cu/CuSO4 (criterion based plus IR drop correction) and meeting the design current.
Cathodic protection installations (pressure pipe line-jetty-tank farm) are periodically monitored under environmental legislation (soil-ground pollution) and safety duties; operating practice sets at least one or two readings per year for potential points, half-year to year on sacrificial systems, and continuous logging plus monthly sight on impressed current (ICCP) systems. Measurement points are recorded with GPS-sketch and values are compared as trends against earlier years.
Potential shifting positive (above the criterion), anode depletion threshold, broken-loose connection, unusable test strip-box, low-current-rectifier power fault, excessive current draw from coating damage and stray-current corrosion traces. Removal: anode-rectifier-connection repair, power boost, new anode-relocation, coating repair, all verified with measurement-trend. The report carries the potential map, current value, anode life estimate and maintenance suggestion — corrosion progress is stopped.